The response of anguilliform fish to underwater sound under an experimental setting

Abstract

AbstractTraditional physical screens designed to prevent fish entering dangerous areas (e.g., turbine intakes) can have negative impacts due to impingement or mechanical abrasion at high velocities. Behavioural deterrents may provide an alternative approach to screening. This study investigated the potential for a continuous broadband sound to modify the behaviour of two endangered species of anguilliform fish: European eel (Anguilla anguilla) and river lamprey (Lampetra fluviatilis). Experiments were conducted in an experimental channel. Eel and lamprey were, respectively, released upstream and downstream of an “acoustic maze”. A single individual released per trial encountered two successive chambers that offered a choice of passage through either an ensonified or a control (ambient noise only) corridor with a speaker turned off. Two possible configurations were tested to control for any lateral bias with positions of the activated speakers reversed. The influence of treatment, chamber, and configuration on route selection, rejection, and time to pass were tested. No influence of any of the three factors on route selection was observed for eel. River lamprey tended to pass through the ensonified corridor more often under Configuration 2 but only in the first chamber. Both species were more likely to reject the ensonified corridors than the controls, and the time taken to pass these routes was greater for those that did so. For eel, the variation in time to pass was greater for the non‐migratory (yellow phase) life stage. Although the acoustic signal used in this study influenced fish behaviour, the response observed would likely be insufficient to induce a strong deterrent effect in the field if used in isolation.